This disclosure relates to flexible containers, and sheet materials from which such containers may be constructed, that may be used in connection with non-immersion dry cleaning processes, and particularly those that take place within a heated clothes dryer. This disclosure includes a description of certain reusable flexible containers in the form of bags in which garments or other articles to be cleaned using such processes may be brought into operative contact with a cleaning agent in a way that (1) encourages efficient, thorough and uniform cleaning or freshening of the articles, and (2) removes, as well as discourages the formation of, wrinkles from the articles. This disclosure further includes a description of certain preferred mechanical performance features associated with such bags.
Water-based laundering and non-aqueous-based dry cleaning processes are fundamentally different, but both are commonly used to clean certain kinds of textile fabrics found in the home. Each process is generally capable of removing soil and odors and imparting the fabrics with a clean, fresh appearance and fragrance. However, in many instances, laundering cannot be used because of the likelihood of undesirable consequences, such as differential shrinkage of the garment""s constituent materials, which can cause garment distortion, seam puckering, and distortion of sensitive fabric surface patterns. Additionally, laundering can cause the undesirable bleeding or blending of dyes on a fabric that can affect not only that fabric but other fabrics being laundered at that time. Furthermore, some oily soils are not readily removed by laundering.
Because of these characteristics of laundering, some textile products require a non-aqueous dry cleaning process for satisfactory cleaning. Traditionally, such dry cleaning processes have been solvent immersion-type processes that are available only at commercial or industrial facilities, and have been relatively costly, time consuming, and inconvenient when compared with home laundering. However, these disadvantages have been considered inevitable consequences of having to clean xe2x80x9cdry clean onlyxe2x80x9d textile articles.
Recently, various processes have been developed by which the advantages of dry cleaning can be achieved in a cleaning system that uses the drying cycle of an ordinary residential clothes dryer. These processes, which rely upon the movement of cleaning vapors or gases (these two terms shall be used interchangeably herein) and which are roughly analogous to steam distillation processes, vary in terms of the formulation of the cleaning composition to be used and other details, but generally share common features.
Among these features is the use of a container, most frequently a bag, within which the textile articles and the cleaning composition or agent (these two terms shall be used interchangeably) are brought into operative contact. The articles and a cleaning composition or agent are placed in the bag (the cleaning agent may have a separate receptacle within the bag, and even may already be present in the bag), the bag opening is secured, and the bag is placed in a residential gas or electric clothes dryer. The heat and tumbling action associated with the drying cycle of the dryer causes the cleaning agent to volatilize or otherwise come into contact with the textile articles. The cleaning agent moistens and removes soils from the articles; it is also speculated that, in some cases, some soils on the articles may be at least partially volatilized by the heat from the dryer. In any case, the heat and motion imparted by the dryer promote the formation of a vapor or gas comprised of the cleaning agent and vaporized soil. This vapor is purged on a more-or-less continuous basis from the bag during the dryer cycle through vents or other gas-permeable areas associated with the bag.
Once outside the bag, the vapor-laden air is removed from the interior of the dryer in the same way moist air is removed during a regular drying cycle. The expelled vapors from inside the bag are replaced by relatively fresh, dry air from within the dryer. This process drives the non-equilibrium state in the bag in the direction of causing additional vaporization of cleaning agent and soil, which perpetuates the cleaning action until the cleaning agent is exhausted or the cleaning cycle is stopped. For purposes of discussion herein, such processes will be referred to as non-immersion dry cleaning processes or, more simply, as dry cleaning processes. Although the process is described in terms of a home dry cleaning process using a residential clothes dryer, it is contemplated that the bag construction principles described herein can be used advantageously in similar non-immersion dry cleaning processes that are done in a commercial setting, using commercial or industrial-sized dryers and loads, with bags that are appropriately sized and constructed to accommodate larger loads, extended repeated use, or other commercial requirements.
The design and mechanical performance of the container or bag can have a dramatic effect on the results of these non-immersion dry cleaning processes. Assuming that a bag has the requisite heat resistance and durability, a preferred bag has two fundamental characteristics: (1) an internal space (in terms of both size and shape) capable of providing and maintaining a desirable free tumbling volume (as defined herein) appropriate for the volume of articles to be cleaned, and (2) a satisfactory mechanism to effect and promote a substantially continuous exchange of gases into and out of the bag as the cleaning cycle progresses.
If the bag, while being tumbled by the dryer, has an interior size and shape that promotes full and unencumbered tumbling of the individual articles in the bag, the articles are much more likely to be exposed to the cleaning agent and be cleaned in a thorough and wrinkle-free way. Additionally, because of the essential role that the cleaning vapors have on the efficacy of the process, the articles are much more likely to be cleaned satisfactorily if the bag promotes the proper exchange of gases between the inside and outside of the bag during the cleaning cycle. However, excessive venting can lead to premature exhaustion of cleaning vapors. When this occurs, the supply of cleaning vapor is exhausted before the articles are sufficiently clean and before the cleaning cycle is complete. It is speculated that this may cause the interior of the bag to overheat, may lead to unacceptable shrinkage of the articles being cleaned, and may encourage the setting of wrinkles in such articles.
However, if the bag is to deliver superior cleaning performance, the intrinsic venting characteristics of the bag are merely one of several variables, including the shape of the interior volume, the slickness of the interior walls, the amount of cleaning composition, and the load size, that must be considered. We have found that, surprisingly, the establishment and maintenance of a satisfactory free tumbling space inside the bag when in use appears to affect both the unencumbered tumbling aspect and the gas exchange aspectxe2x80x94effective tumbling appears to be an important mechanism in both distributing and dispersing the cleaning agent among the articles to be cleaned, and, in conjunction with appropriate vents or other openings in the bag, in the exchange of gases between the inside of the bag and the inside of the dryer. We have additionally found that the geometric configuration of the bag, and the mechanical naturexe2x80x94in particular, the stiffness and slicknessxe2x80x94of the wall material from which the bag is constructed, can have a dramatic effect on free tumbling space and the overall efficacy of the dry cleaning process. Specifically, durable bags that (1) have an appropriately sized and shaped interior volume, (2) are constructed from a design and with materials that provide an overall bag structure that is sufficiently stiff to substantially maintain the bag""s interior configuration when in use, and (3) have an appropriately slick interior that encourages the desirable distribution of articles within the bag without promoting the collapse of the bag, have been found to be well suited for non-immersion dry cleaning use.
Of course, other characteristics must also be considered. For example, it is also desirable that the bag is easy and inexpensive to manufacture and easy to fold for marketing and storage purposes. Further desirable bag characteristics include (1) relatively high durability (including resistance to the high temperatures that could be encountered in a dryer), to allow re-use for a number of cleaning cycles, (2) relatively high use-to-use performance uniformity, to assure dependable and predictable cleaning results, (3) good practical appeal to the userxe2x80x94be easy to open and close, generate minimal noise during use, etc., and (4) good marketability and appeal for the supplier, for example, having a bag surface that provides a good texture or xe2x80x9cfeelxe2x80x9d yet allows for the printing of trademarks, promotional or instructional messages, etc.